A Research On Performance Of Desuperheater And Decompressor When Steam Discharge

The desuperheater and decompressor is the key equipment of the steam dump system for its important role in ensuring the safety of the steam system. The desuperheater and decompressor works by multistage orifice throttling decompression and reduction temperature by water spray. So , researching on spray atomization characteristic and orifice throttling characters can provide a significant reference for the design and optimization of the desuperheater and decompressor.The present paper discusses the characteristics of water-spraying and atomization according to theoretical and experimental research. Based on experiment and numerical simulation, the characteristics of throttling is examined . The performance of test sample with single hole, test samples with five holes as well as opposite-spray test samples under different air flow rate and water flow rate is studied by using high speed camera. The critical flow rate of orifices with different hole area ratios and hole numbers is measured respectively under different inlet pressure. The pressure distribution within two orifices is researched with changes of hole area on secondary orifices.Three important characteristics—the up trace of atomization spraying flow,the break point of flow columns, the diameter of droplets—is obtained through theoretical and experimental research, based on which fitting expressions are presented. The experiment shows better atomization when the spraying angle is about 135° ?Based on experimental data, the fitting expressions of critical flow rate and the pressure curve within two orifices are presented? The research also shows that lager hole-area ratio causes larger critical flow factor and the critical flow factor of multiple-hole orifices is bigger than that of singe-hole orifice. The larger hole area of secondary orifice has significant influence on the pressure within secondary orifice by lowering the pressure. The main mechanism of decompression caused by orifice is steam vortexes, which appear behind orifice, transform kinetic energy to thermal energy. The direction of holes does not have significant effect on critical flow rate and the maximal Mach number whereas it can influence the changes of pressure under low pressure conditions obviously.